Data lineage based multi-data store recovery

ABSTRACT

Embodiments disclosed herein provide systems, methods, and computer readable media for data lineage based multi-data store recovery. In a particular embodiment, a method provides identifying first data in a first table of a plurality of tables stored in a plurality of data stores and restoring the first data to a first correct version of the first data in a prior version of the first table. The method further provides identifying a second table of the plurality of tables that descends from the first table and includes second descendent data that stems from the first data. The method also provides restoring the second descendent data to a second correct version of the second descendent data in a prior version of the second table.

RELATED APPLICATIONS

This application is related to and claims priority to U.S. ProvisionalPatent Application 62/099,747, titled “DATA LINEAGE BASED MULTI-DATASTORE RECOVERY,” filed Jan. 5, 2015, and which is hereby incorporated byreference in its entirety.

TECHNICAL BACKGROUND

Data in modern enterprises may flow through many different data stores.Thus, a data table in one system may be used to generate data in tablesof one or more other systems. For example, a data table in Oracle may betransformed into multiple tables in Hadoop and Teradata that change inboth shape and form. The transformations of the original data table arenecessary because each derivative data table may be used for a differentpurpose. Regardless, if a data table containing bad data is propagatedinto other tables, the data in those other tables likewise becomes badand exacerbates the problem caused by the original bad data.

OVERVIEW

Embodiments disclosed herein provide systems, methods, and computerreadable media for data lineage based multi-data store recovery. In aparticular embodiment, a method provides identifying first data in afirst table of a plurality of tables stored in a plurality of datastores and restoring the first data to a first correct version of thefirst data in a prior version of the first table. The method furtherprovides identifying a second table of the plurality of tables thatdescends from the first table and includes second descendent data thatstems from the first data. The method also provides restoring the seconddescendent data to a second correct version of the second descendentdata in a prior version of the second table.

In some embodiments, the method provides identifying a third table ofthe plurality of tables that descends from the first table and includesthird descendent data that stems from the first data. In thoseembodiments, the method also provides restoring the third descendentdata to a third correct version of the third descendent data in a priorversion of the third table.

In some embodiments, the third table descends from the first table as aresult of descending from the second table.

In some embodiments, the method further provides running a versioningtool to identify the prior version of the second table from a pluralityof versions of the second table and identify the prior version of thethird table from a plurality of versions of the third table.

In some embodiments, the first data comprises data having one or moreerrors and the first correct version includes the first data prior tothe errors.

In some embodiments, identifying the second table comprises running adata lineage tool to identify tables of the plurality of tables thatdescend from the first table.

In some embodiments, the method provides running a versioning tool toidentify the prior version of the first table from a plurality ofversions of the first table.

In some embodiments, the prior version of the first table comprises amost recent version of the first table having the first correct versionof the first data.

In some embodiments, the prior versions of the first and second tablesexist in a secondary data repository.

In another embodiment, a non-transitory computer readable storage mediumis provided having instructions stored thereon. The instructions, whenexecuted by a data recovery system, direct the data recovery system toidentify first data in a first table of a plurality of tables stored ina plurality of data stores and restore the first data to a first correctversion of the first data in a prior version of the first table. Theinstructions further direct the data recovery system to identify asecond table of the plurality of tables that descends from the firsttable and includes second descendent data that stems from the firstdata. The instructions also direct the data recovery system to restorethe second descendent data to a second correct version of the seconddescendent data in a prior version of the second table.

In yet another embodiment, a data recovery system is provided includingone or more computer readable storage media, a processing systemoperatively coupled with the one or more computer readable storagemedia, and program instructions stored on the one or more computerreadable storage media. The instructions, when read and executed by theprocessing system, direct the processing system to identify first datain a first table of a plurality of tables stored in a plurality of datastores and restore the first data to a first correct version of thefirst data in a prior version of the first table. The programinstructions further direct the processing system to identify a secondtable of the plurality of tables that descends from the first table andincludes second descendent data that stems from the first data. Theprogram instructions also direct the processing system to restore thesecond descendent data to a second correct version of the seconddescendent data in a prior version of the second table.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a computing environment for performing data lineagebased multi-data store recovery.

FIG. 2 illustrates an operation of the computing environment to performdata lineage based multi-data store recovery.

FIG. 3 illustrates a data table tree in a scenario of performing datalineage based multi-data store recovery.

FIG. 4 illustrates another computing environment for performing datalineage based multi-data store recovery.

FIG. 5 illustrates an operation of the other computing environment toperform data lineage based multi-data store recovery.

FIG. 6 illustrates another operation of the other computing environmentto perform data lineage based multi-data store recovery.

FIG. 7 illustrates an operational scenario of the computing environmentperforming data lineage based multi-data store recovery.

FIG. 8 illustrates a data recovery system for protecting data based onimportance of the data.

DETAILED DESCRIPTION

The following description and associated figures teach the best mode ofthe invention. For the purpose of teaching inventive principles, someconventional aspects of the best mode may be simplified or omitted. Thefollowing claims specify the scope of the invention. Note that someaspects of the best mode may not fall within the scope of the inventionas specified by the claims. Thus, those skilled in the art willappreciate variations from the best mode that fall within the scope ofthe invention. Those skilled in the art will appreciate that thefeatures described below can be combined in various ways to formmultiple variations of the invention. As a result, the invention is notlimited to the specific examples described below, but only by the claimsand their equivalents.

The various embodiments disclosed herein provide for recovery from baddata that has propagated across multiple data stores. In particular,many different systems may use the same data or some derivation ortransformation of that data. For example, a data table in an Oracledatabase may be transformed (e.g. reformatted, reshaped, etc.) into oneor more data tables used by a Hadoop or Teradata system. If the data inthe original table is bad (e.g. incorrect, corrupt, errored, orotherwise), then any table created from the original table will also bebad. Accordingly, the bad data will have to be traced to all subsequenttables if one hopes to remedy all instances of the bad data.

FIG. 1 illustrates computing environment 100 in an example scenario ofdata lineage based multi-data store recovery. Computing environment 100includes data recovery system 101 and data stores 1-N containing datatables 1-N respectively. Data recovery system 101 and data stores 1-Ncommunicate over communication links 111. While each of tables 1-N areillustrated in this example as being in separate data stores, it shouldbe understood that each data store may contain more than one table oftables 1-N. Similarly, it is possible in some examples that all oftables 1-N are stored in a single data store. Thus, any number of tablesand data stores may be used in any combination.

In operation, data recovery system 101 uses data lineage and dataversioning tools to track data that propagates between tables 1-N. Oncethe data lineage tool has determined the lineage of data amongst tables1-N, bad data identified in one of tables 1-N can be traced to othertables that include data that has been copied, derived, transformed, orotherwise based upon the bad data. The data versioning tool is then usedto identify a previous version of data for each table that did notinclude data based upon the bad data. Data recovery system 101 thenrestores each affected table with the respective previous versions ofthe data. Advantageously, data recovery system 101 is able to find andrestore all instances of bad data that propagated to other tables anddata stores from an original instance of bad data.

FIG. 2 illustrates operation 200 of computing environment 100 forperforming data lineage based multi-data store recovery. Operation 200includes data recovery system 101 determining parent-child relationshipsbetween tables 1-N (step 201). In other words, the data lineage tooldetermines whether data in any given table of tables 1-N is a copy,transformation, derivation, or is otherwise based upon data in anothertable. The data lineage tool may determine the data lineage of tables1-N after the data in each table is populated or may track the datalineage as the data in each table is populated.

Data recovery system 101 identifies bad data in a first table of tables1-N (step 202). The bad data may be identified from user inputindicating that data in the first table is bad, from an error detectionprocess determining that the data is bad, or from any other method bywhich bad data may be identified. Using the data lineage determined bythe data lineage tool, data recovery system 101 identifies tables oftables 1-N that descend from the first table and, therefore, are alsoinclude bad data by virtue of their dependency upon the first table(step 203). In some examples, rather than maintaining a data lineage forall of tables 1-N, the data lineage tool may only determine the datalineage of a table until bad data is identified.

Using a versioning tool, data recovery system 101 finds and restoresdata in the first table to a most recent good version of the data in thefirst table (step 204). Specifically, data recovery system 101 maymaintain or have access to one or more data stores that store pastversions of data contained in the first table. Thus, data recoverysystem 101 uses the version tool to traverse the available versions toidentify a version containing data before the bad data appeared in thefirst table. In some cases, that identified version may be used only toreplace the bad data while, in other cases, the version may be used toreplace all of the data in the first table.

Likewise, data recovery system 101 performs similar actions for each ofthe descendent tables identified by the lineage tool. In particular,data recovery system 101 uses the versioning tool to determine a mostrecent good version of data in each descendent table that is based uponthe most recent good version of the data in the first table (step 205).In other words, the versioning tool accesses a data store that storespast versions of the data in each descendent table and finds the mostrecent version of data that is not affected by the bad data propagatedfrom the first table. The timestamp on the versions may differ betweendescendent tables since the bad data may have been propagated into eachdescendent table at different times and the timing/schedule for creationof the versions may differ. Data recovery system 101 then restores eachdescendent table to its respective most recent version (step 206). Aswith the restoration of the first data table above, each descendenttable may merely have the bad data replaced or may replace all data inthe table with the determined version.

Therefore, upon completion of operation 200, data recovery system 101 isable to find all descendent table instances of bad data propagated froman ancestor table and recover prior versions of the table data to removethe bad data from all tables.

Referring back to FIG. 1, data recovery system 101 comprises a computersystem and communication interface. Data recovery system 101 may alsoinclude other components such as a router, server, data storage system,and power supply. Data recovery system 101 may reside in a single deviceor may be distributed across multiple devices. Data recovery system 101could be an application server(s), a personal workstation, or some othernetwork capable computing system—including combinations thereof.

Data stores 1-N are maintained within one or more data storage systemseach comprising a communication interface and one or more non-transitorystorage medium, such as a disk drive, flash drive, magnetic tape, datastorage circuitry, or some other memory apparatus. The data storagesystems may also include other components such as processing circuitry,a router, server, data storage system, and power supply. The datastorage systems may reside in a single device or may be distributedacross multiple devices. All or portions of the data storage systemscould be integrated within the components of data recovery system 101.

Communication links 111 could be internal system busses or use variouscommunication protocols, such as Time Division Multiplex (TDM), InternetProtocol (IP), Ethernet, communication signaling, Code Division MultipleAccess (CDMA), Evolution Data Only (EVDO), Worldwide Interoperabilityfor Microwave Access (WIMAX), Global System for Mobile Communication(GSM), Long Term Evolution (LTE), Wireless Fidelity (WIFI), High SpeedPacket Access (HSPA), or some other communication format—includingcombinations thereof. Communication links 111 could be direct links ormay include intermediate networks, systems, or devices.

FIG. 3 illustrates data table tree 300 in an exemplary embodiment. Datatable tree 300 illustrates the parent-child relationships between tables1-11, which comprise a subset of tables 1-N, as determined by the datalineage tool of data recovery system 101 in operation 200. In thisexample, data recovery system 101 determines that table 5 includes baddata, which is indicated by the dashed border. The lineage representedby tree 300 is then used by data recovery system 101 to determine thatthe bad data in table 5 has propagated to tables 6-11, which is alsoindicated by dashed borders. The versioning tool of data recovery system101 is used to find a most recent version of each of tables 5-11 thatdoes not include data based on the bad data of table 5. Data recoverysystem 101 recovers the data of tables 5-11 from the found most recentversions of each table.

FIG. 4 illustrates computing environment 400 for performing data lineagebased multi-data store recovery. Computing environment 400 includes datarecovery system 401, primary data repository 402, secondary datarepository 403, and communication network 404. Data recovery system 401and communication network 404 communicate over communication link 411.Primary data repository 402 and communication network 404 communicateover communication link 412. Secondary data repository 403 andcommunication network 404 communicate over communication link 413.

While shown as a single element, primary data repository 402 maycomprise multiple data stores similar to those shown in computingenvironment 100, which each individually connect to communicationnetwork 404. As such, tables 421-424 may be co-located on a single datastore or may be located on different data stores. Similarly, secondarydata repository 403 may also comprise multiple data stores for storingincremental data versions of data tables 421-424. In some cases, atleast a portion of the incremental data versions stored in secondarydata repository 403 may instead be stored in primary data repository 402along with data tables 421-424. Of the incremental data versions storedin secondary data repository 403, data table versions 421.1-N areversions of data table 421 with data table version 421.1 being the mostrecent. Likewise, data table versions 422.1-N are versions of data table422 with data table version 422.1 being the most recent, data tableversions 423.1-N are versions of data table 423 with data table version423.1 being the most recent, and data table versions 424.1-N areversions of data table 424 with data table version 424.1 being the mostrecent. While shown in columns, the creation times for the data tableversions in a single column are not necessarily the same, which may bedue to latency, differing backup schedules between data tables 421-424,differing backup schemes between data tables 421-424, or for some otherreason that version creation may differ—including combinations thereof.

FIG. 5 illustrates operation 500 of the other computing environment toperform data lineage based multi-data store recovery. In operation 500,data recovery system 401 identifies data in a first table stored inprimary data repository 402 (501). In this example, the first table isdata table 421, which may be identified based on input from a userindicating that the particular data within data table 421 is bad (i.e.errored, corrupt, or otherwise improper). Data recovery system 401 thenrestores the identified data to a correct version of the data in one ofdata table versions 421.1-N in secondary data repository 403 (502).Preferably, the correct version of the data that is used to restore islocated in a most recent data table version having the correct versionof the data. For example, the data table version 421.1 may still includethe identified bad data while the next most recent data table version,data table version 421.2, includes the correct version of the data. Datatable version 421.2 would therefore be used for the restore.

Data recovery system 401 further identifies a second table that descendsfrom the first table and includes descendent data that stems from thedata identified above in data table 421 (503). In this example, datatable 423 is determined to descend from data table 421 and havedescendent data stemming from data table 421's identified data.Descendent data is considered to stem from data table 421's identifieddata, if it is a duplicate of that identified data, is a derivation ofor from the identified data, includes the identified data, or wasotherwise created based on the identified data. Like for data table 421above, data recovery system 401 then restores the descendent data to acorrect version of the descendent data found in a, preferably mostrecent, data table version 423.1-N.

In the above example, only one data table was identified as descendingfrom data table 421 and having the requisite descendent data. However,any number of data tables may satisfy that criteria in other examplesand steps 503 and 504 may be applied to those data tables as well.

FIG. 6 illustrates operation 600 of computing environment 400 to performdata lineage based multi-data store recovery. In operation 600, datarecovery system 401 identifies bad data in data table 421 (601). The baddata may be indicated by a user or from some other source. Even thoughthe bad data is identified in data table 421 again in this example, thebad data could have been identified in any other data table should thebad data exist therein. Data recovery system 401 uses a versioning toolto identify the most recent correct version of the bad data from datatable versions 421.1-N (602). The versioning tool may be the same toolthat was used to create the versions or may be a different tool. Thecorrect version of the data may be identified based on when the bad datafirst showed up as a change in the data table versions. For example, ifdata table version 421.2 includes the bad data as an incremental changeto data table 421, then data recovery system 401 may assume that datatable version 421.3 represents the most recent data table version tohave the correct data (i.e. before the data changed to the bad data).

Once identified, data recovery system 401 can restore the bad data tothe corrected data from the identified version (603). In some cases,only the bad data itself is restored to the corrected version of thedata while in other cases data table 421 as a whole is restored to theversion having the correct data version.

Operation 600 further provides that data recovery system 401 runs a datalineage tool to find descendent data tables to data table 421 (604). Insome examples, the data lineage tool may have already been run or mayrun continuously to track the lineage of data included in data tables421-424. The data lineage tool is able to identify data tables thatinclude data from data table 421. More specifically, the data lineagetool is able to indicate which data tables and which data therein stemsfrom the identified bad data in data table 421.

Once a descendent data table having descendent data is identified, thedata versioning tool is used to find a preferably most recent version ofthe descendent data table that includes descendent data that descendsfrom a correct version of the identified bad data in data table 421(605). The version tool may identify the version of the descendent datatable in the same manner as in step 602. After identifying the version,the descendent data is restored from that version into the descendentdata table (606). As in step 603, the whole data table version may berestored or just the portion effected by the bad data.

Steps 605 and 606 repeat, or are performed concurrently, for each ofdescendent data tables that were identified at step 604. Due to theamount of time needed for the bad data to propagate to descendent datatables and the potentially different scheduling for creating versions ofthe respective data tables, the creation times of each data tableversion used to restore each respective descendent data table are likelynot the same. Therefore, using operation 600 allows for all bad datastemming from the identified bad data in data table 421 to beautomatically found and restored to corrected versions regardless ofwhen the data table version containing that corrected data was created.

FIG. 7 illustrates operational scenario 700 of computing environment 400for performing data lineage based multi-data store recovery. Data tables421-424 are illustrated with an example descendent relationship that maybe generated from the results of running a data lineage tool, as in step604 of operation 600. At step 1 in scenario 700, data 721 is identifyingas being bad data. Then at step 2, the lineage shows that data tables422 and 423 descend from data table 421 with data 721 as well. Datatable 424 further descends from data table 421 with data 721 by way ofdescending from data table 423. It should be understood that, while eachof data tables 421-424 is shown to include data 721, data 721 in each ofdata tables 422-424 may be derived or otherwise stem from data 721rather than being a direct copy. Additionally, while not shown, otherdata tables may be stored in primary data repository 402 that do notdescend from data table 421 and/or do not include data stemming fromdata 721, which would therefore not be identified in step 2.

At step 3, data table versions for each of data tables 421-424 areidentified that contain correct data to restore the bad data 721.Specifically, in this example, data table version 421.3 is identifiedfor data table 421, data table version 422.2 is identified for datatable 422, data table version 423.2 is identified for data table 423,and data table version 424.1 is identified for data table 424. Thoseidentified data table versions are then used to restore each respectivedata table 421-424 at step 4. In this example, the entire table isrestored, although just the bad data 721 may be restored with correctdata. Accordingly, upon completion of scenario 700, data 721 needed toonly be identified once with respect to data table 721 and then all baddata stemming from data 721 is automatically identified and correctedacross all tables in primary data repository 402.

FIG. 8 illustrates data recovery system 800. Data recovery system 800 isan example of data recovery system 101, although system 101 may usealternative configurations. Data recovery system 800 comprisescommunication interface 801, user interface 802, and processing system803. Processing system 803 is linked to communication interface 801 anduser interface 802. Processing system 803 includes processing circuitry805 and memory device 806 that stores operating software 807.

Communication interface 801 comprises components that communicate overcommunication links, such as network cards, ports, RF transceivers,processing circuitry and software, or some other communication devices.Communication interface 801 may be configured to communicate overmetallic, wireless, or optical links. Communication interface 801 may beconfigured to use TDM, IP, Ethernet, optical networking, wirelessprotocols, communication signaling, or some other communicationformat—including combinations thereof.

User interface 802 comprises components that interact with a user. Userinterface 802 may include a keyboard, display screen, mouse, touch pad,or some other user input/output apparatus. User interface 802 may beomitted in some examples.

Processing circuitry 805 comprises microprocessor and other circuitrythat retrieves and executes operating software 807 from memory device806. Memory device 806 comprises a non-transitory storage medium, suchas a disk drive, flash drive, data storage circuitry, or some othermemory apparatus. Operating software 807 comprises computer programs,firmware, or some other form of machine-readable processinginstructions. Operating software 807 includes data lineage tool 808,versioning tool 809, and bad data identification module 410. Operatingsoftware 807 may further include an operating system, utilities,drivers, network interfaces, applications, or some other type ofsoftware. When executed by circuitry 805, operating software 807 directsprocessing system 803 to operate Data recovery system 800 as describedherein.

In particular, bad data identification module 410 directs processingsystem 803 to identify first data in a first table of a plurality oftables stored in a plurality of data stores. Versioning tool 809 directsprocessing system 803 to restore the first data to a first correctversion of the first data in a prior version of the first table. Datalineage tool 808 directs processing system 803 to identify a secondtable of the plurality of tables that descends from the first table andincludes second descendent data that stems from the first data.Versioning tool 809 further directs processing system 803 to restore thesecond descendent data to a second correct version of the seconddescendent data in a prior version of the second table.

The above description and associated figures teach the best mode of theinvention. The following claims specify the scope of the invention. Notethat some aspects of the best mode may not fall within the scope of theinvention as specified by the claims. Those skilled in the art willappreciate that the features described above can be combined in variousways to form multiple variations of the invention. As a result, theinvention is not limited to the specific embodiments described above,but only by the following claims and their equivalents.

What is claimed is:
 1. A non-transitory computer readable storage mediumhaving instructions stored thereon for performing data lineage basedmulti-data store recovery, the instructions, when executed by a datarecovery system, direct the data recovery system to: identify first datain a first table of a plurality of tables stored in a plurality of datastores; restore the first data to a first correct version of the firstdata in a prior version of the first table; identify a second table ofthe plurality of tables that descends from the first table and includessecond descendent data that stems from the first data; and restore thesecond descendent data to a second correct version of the seconddescendent data in a prior version of the second table.
 2. Thenon-transitory computer readable storage medium of claim 1, wherein theinstructions further direct the data recovery system to: identify athird table of the plurality of tables that descends from the firsttable and includes third descendent data that stems from the first data;and restore the third descendent data to a third correct version of thethird descendent data in a prior version of the third table.
 3. Thenon-transitory computer readable storage medium of claim 2, wherein thethird table descends from the first table as a result of descending fromthe second table.
 4. The non-transitory computer readable storage mediumof claim 2, wherein the instructions further direct the data recoverysystem to: run a versioning tool to identify the prior version of thesecond table from a plurality of versions of the second table andidentify the prior version of the third table from a plurality ofversions of the third table.
 5. The non-transitory computer readablestorage medium of claim 1, wherein the first data comprises data havingone or more errors and the first correct version includes the first dataprior to the errors.
 6. The non-transitory computer readable storagemedium of claim 1, wherein to identify the second table the instructionsdirect the data recovery system to: run a data lineage tool to identifytables of the plurality of tables that descend from the first table. 7.The non-transitory computer readable storage medium of claim 1, whereinthe instructions further direct the data recovery system to: run aversioning tool to identify the prior version of the first table from aplurality of versions of the first table.
 8. The non-transitory computerreadable storage medium of claim 1, wherein the prior version of thefirst table comprises a most recent version of the first table havingthe first correct version of the first data.
 9. The non-transitorycomputer readable storage medium of claim 1, wherein the prior versionsof the first and second tables exist in a secondary data repository. 10.A method of performing data lineage based multi-data store recovery, themethod comprising: identifying first data in a first table of aplurality of tables stored in a plurality of data stores; restoring thefirst data to a first correct version of the first data in a priorversion of the first table; identifying a second table of the pluralityof tables that descends from the first table and includes seconddescendent data that stems from the first data; and restoring the seconddescendent data to a second correct version of the second descendentdata in a prior version of the second table.
 11. The method of claim 10,further comprising: identifying a third table of the plurality of tablesthat descends from the first table and includes third descendent datathat stems from the first data; and restoring the third descendent datato a third correct version of the third descendent data in a priorversion of the third table.
 12. The method of claim 11, wherein thethird table descends from the first table as a result of descending fromthe second table.
 13. The method of claim 11, further comprising:running a versioning tool to identify the prior version of the secondtable from a plurality of versions of the second table and identify theprior version of the third table from a plurality of versions of thethird table.
 14. The method of claim 10, wherein the first datacomprises data having one or more errors and the first correct versionincludes the first data prior to the errors.
 15. The method of claim 10,wherein identifying the second table comprises: running a data lineagetool to identify tables of the plurality of tables that descend from thefirst table.
 16. The method of claim 10, further comprising: running aversioning tool to identify the prior version of the first table from aplurality of versions of the first table.
 17. The method of claim 10,wherein the prior version of the first table comprises a most recentversion of the first table having the first correct version of the firstdata.
 18. The method of claim 10, wherein the prior versions of thefirst and second tables exist in a secondary data repository.
 19. A datarecovery system to perform data lineage based multi-data store recovery,the data recovery system comprising: one or more computer readablestorage media; a processing system operatively coupled with the one ormore computer readable storage media; and program instructions stored onthe one or more computer readable storage media that, when read andexecuted by the processing system, direct the processing system to:identify first data in a first table of a plurality of tables stored ina plurality of data stores; restore the first data to a first correctversion of the first data in a prior version of the first table;identify a second table of the plurality of tables that descends fromthe first table and includes second descendent data that stems from thefirst data; and restore the second descendent data to a second correctversion of the second descendent data in a prior version of the secondtable.
 20. The data recovery system of claim 19, wherein the programinstructions further direct the processing system to: identify a thirdtable of the plurality of tables that descends from the first table andincludes third descendent data that stems from the first data; andrestore the third descendent data to a third correct version of thethird descendent data in a prior version of the third table.